Scoring device for coatings



June 25, 1968 G. GEREK ET Al. 3,389,463

SCORING DEVICE FOR COATINGS Filed Oct.

INVENTOR GENE @BEEK RALPH ,ac/c5190# QAM@ M,

A ORNEYS United States Patent O This invention relates to a devi-ce for scoring or marking a layer of material adhering to a substrate and, more particularly, to a durable, self-cleaning instrument for making parallel lines of reproducible depth in a coating, such as paint.

At present, a widely-used test of the adhesion of coating material films is that which entails Scor-ing the coating film and applying tape to the scored surface. It is usually necessary to score at least two lines in the coating surface and preferably a matrix of intersecting parallel lines is formed. When the tape is pulled away, the amount of coating material adhering to the tape is considered to be inversely proportional to the adhesion of the coating lm to the substrate.

In order to standardize the test, it is essential that each scoring operation result in a series of marks of substantially equivalent depth. That is, the scoring must be reproducible, since a failure to achieve consistency would lead to inaccurate adhesion measurements. :For example, if two identical coated panels were scored to different depths, the test would likely render an erroneous compar-ison.

Although this adhesion test constitutes a simple and eifective measurement of coating adhesion, and is there :fore of wide commercial interest, its use has been limited 'because of the diiiiculty in obtaining reproducible scorings of consistent depth, In one such test, for example, a sharp scalpel is used for iirst scoring 1/lG-inch apart parallel lines and then additional parallel lines, at right angles to the iirst, to form the matrix. The diiiiculty in obtaining consistency by means of this method is obvious.

Another method utilizes a series of spaced-apart cutting edges, such as, for example, razor |blades or ci-rcular cutting edges similar to those utilized in the instrument of this invention, Devices using razor blades or similar sharp edges, however, are not practical because the blades dull very quickly when used on steel panels. As a result, the blades must lbe continually replaced or remachined if accurate measurements are to be obtained.

Scoring tools having circular cutting edges were orig/i-` nally designed to remedy the lack of durability caused by dulling of the cutting edges. After each scoring operation, the cutting edges are rotated such that a new section of the cutting edge contacts the lpaint surface. Significant disadvantages remain, however, such as, clogging of the grooves with coating material, which builds up as the surface is scored, and the fact that the yblades must usually be remachined after each complete rotation of the circular edges. The coating build-up is primarily responsible for causing inconsistent scorings along with, and often in conjunction with, the dulling of the edges themselves. lf one portion of the device becomes more clogged with material than another during the `scoring operation, the corresponding edge does not penetrate to the depth of the less clogged edges. It is practically impossible to duplicate on a second coated panel the unevenly scored matrix formed on the ilrst, and any comparisons as to the adhesion of the panels is, therefore, erroneous.

It has now been discovered that an extremely durable and accurate scoring device, having spaced-apart cutting elements and being especially useful `for use in paint lm adhesion tests, is obtained by forming at least one notch across the spaced-apart -cutting elements. Such instrument 3,389,463 Patented June 25, 1958 not only can be easily tooled without adherence to difficult tolerance limitations, but also is self-cleaning during the scoring operation, thereby preventing coating material build-up in the grooves and assuring a uniform removal of film from each line on each cut.

In employing this device, both the spaced-apart cutting elements and the cutting edge formed lby the notch wall are utilized in the scoring operation. That is, the cutting element is drawn across the surface of the material to be scored such that the cutting edges adjacent t-o the notch wall are brought into contact with the surface, thereby enabling both the cutting edges and the notch Wall edge to simultaneously score the material. Depending upon the hardness of the material to be scored, the exertion of slight pressure on the tool against the surface of the material maybe necessary.

FIGURES 1-3 illustrate in detail a specific and preferred embodiment of the scoring device of this invention.

The novel portion of the instrument is the notch which Vis cut or formed across the spaced-apart cutting elements, and this feature is primarily responsible for the remarkable durability and accuracy of the device. As mentioned above, the cutting element is brought into contact with the coating surface such that the edge of the notch itself constitutes a cutting edge. The result is a hybrid cutting element combining the plurality of edges of the spacedapart cutting elements with the cutting edge formed by the notch wall and cutting elements.

This hybridization of cutting elements allows the spaced-apart cutting elements to more eas-ily penetrate the coating, since even slight pulling action will cause the notch edge to dig into the coating surface. Using conventional devices, substantial pressure is normally necessary to cause initial penetration. The employment of such pressure usually results in film buildaup in the grooves, as mentioned above, and Vfurther dulling of the edges themselves. Now, however, using the device of this invention, the scoring device is readily carried out with little or no pressure and no clogging of the grooves.

The notch can be very easily machined since the depth of the notch only serves to collect coating material and, therefore, no critical tolerances need be observed. Moreover, a single tool utilizing this feature vwill last for extremely long periods of time since Aa simple shaving of the notch walls yields a new cutting edge. The notch walls are preferably formed in such manner that they curve slightly inward, that is, that they make an angle with the cutting element of less than 901 and normally between about 60 `and 90. The angle, however, may vary Widely from obtuse to acute, depending on the particular application, and usually is within from about 20 to 120. It is only required that an edge be formed by the notch wall and the cutting element, such element being primarily responsible for the unique properties of the scoring device. Preferably, a plurality of notches is formed across the cutting elements, usually at right angles to the direction of the cutting elements.

Although the drawings specifically describe a tool having circular cutting elements, it is also possible, of course, to utilize other designs, such as, for example, straight cutting elements. It is preferred, however, to utilize circular cutting elements, since the scoring operation is thereby usually most easily performed.

The simplicity of the device, in addition to the properties described above, renders it of significant practical value t0 the entire coating industry. For example, in the automotive finish industry, the device is especially suitable for checking intercoat adhesion of automotive iinishes where assembly line production calls for quick, as well as accurate, adhesion tests.

For a further understanding of the invention, reference may now be had to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a view illustrating Va specic and preferred embodiment of the scoring device of this invention and showing the device in operation.

FIGURE 2 is a close-up view of the cutting edge of the scoring device of FIGURE 1.

FIGURE 3 is a side View of the scoring device of FIGURE l, illustrating how the coating Surface is scored.

Referring in more detail to the drawings, FIGURE 1 shows a scoring device as it is forming a cross-hatch matrix on the surface of a coated panel 1. The handle 2 is attached to the circular cutting head 3 by means of yoke 4. The circular cutting head 3 is a roller rotatable on a pin, not shown, into which screw 5 is inserted for tightening the yoke and thereby locking the circular cutting head during the cutting operation. A plurality of circular cutting elements 6, with grooves 7, make up the periphery of the cutting head. Notches 8 are intermittently formed at right angles to the circular cutting elements 6. In forming the matrix 9, the device is manually drawn across the coating surface with the circular cutting elements 6 immediately adjacent to the notch 8 being in contact with the coating surface. Normally, the weight of the cutting head 3 is suicient, along with the drawing action, to penetrate the surface, otherwise slight downward pressure exerted on handle 2 may be needed.

FIGURE 2 shows in dctail the cutting element of the scoring device of FIGURE 1 and also illustrates, as a preferred feature of the device, the inward curvature of the notch wall 10. Here, the angle of curvature between the cutting element 6 and the notch wall 10 is approximately 75.

FIGURE 3 shows a side view of the scoring device of FIGURE 1 illustrating how the removed coating material 11 is collected in the notch 8, thereby preventing coating material build-up in the grooves 7, shown by dotted lines.

A tool embodying the principles of this invention was machined out of steel, according to the design of FIG- URE 1. The instrument consists of a handle attached to a rotatable roller having its outer surface 13 spaced-apart circular cutting elements with 4 notches, of relatively shallow depth, cut at approximately right angles across the cutting elements. The device can be locked into position by tightening a screw inserted into a yoke which connects the roller and the handle. When drawn across the surface of a steel panel, having a coating comprising polyvinylidene fluoride thereon, with the exertion of slight downward pressure, the coating surface was evenly scored.

The scoring device of this invention is especially useful in adhesion tests for conventional organic coatings, such as paints, lacquers, owable resins, and the like, applied to metallic substrates such as tinplate, iron, steel, ctc. Specic coatings which can be scored include, for example, those comprising vinyl halide resins, epoxy resins, hydrocarbon resins, alkyd resins, acrylic resins, phenolic resins, and the like. The coating, however, may also be inorganic as, for example, a film of tin on a steel panel or the lm produced on aluminum after treatment with chromic acid or various other chemicals. Similarly, the substrate does not have to be metallic as the device works equally well where wood or plastic substrates are employed.

Although the scoring device has been described in relation to a cross-hatch adhesion test, it should be clear that this specific application in no way limits or restricts the use of the device to such test since it is suitable in any application where it is necessary to mark a layer of material adhering to a substrate or any solid material capable of being scored.

An example of a different adhesion test in which this device may be employed is described in U.S. Patent 2,431,974, where a plurality of parallel or bisecting lines or grooves are formed through the coating lm of decreasing spacing such that lateral stress is placed on the intervening coating material to thereby determine the mechanical measure of the bond between a paint coating and the substrate on which it is applied. Such application also demonstrates that the device is not limited to manual operations but may also be incorporated into a suitable machine for accomplishing the same.

The device may be constructed of any material which can be formed according to the design as disclosed and which is capable of scoring or marking solid substances, such as those described above Accordingly, the instrument is preferably made of a metallic substance, especially steel, although brass, nickel, iron, etc., may also be employed depending upon the particular properties required.

The specific and preferred embodiments described above are believed to best enable one skilled in the art to make and use this invention and it is noted that various changes and modications of the disclosed design are possible without departing from the spirit thereof.

We claim:

1. A tool for scoring solid material comprising a handle and a cutting head, said cutting head defining an enlarged member having a pair of side surfaces and an arcuate peripheral surface disposed therebetween, said peripheral surface having a plurality of V-shaped cutting elements, a notch formed in said cutting head across the cutting elements thereof, the boundaries of said notch with said cutting elements defining cutting edges, whereby when the cutting head is drawn across the solid material in the direction of the cutting elements with the cutting edges in Contact with the surface of the solid material, the surface is uniformly and reproducibly scored.

2. The tool of claim 1 wherein the cutting head is roller-like and capable of being rotated but fixedly mounted on the handle during its use, and has a plurality of spacedapart, circular cutting elements formed with notches cut at right angles across the circular cutting elements, the walls of the notches forming an angle of from about 20 to 120 with the cutting elements.

3. The tool of claim 1 wherein the cutting head is rollerlike and capable of being rotated but ixedly mounted on the handle during its use, and has a plurality of spacedapart, circular cutting elements formed with notches cut at right angles across the circular cutting elements, the walls of the notches forming an angle with the cutting element of less than References Cited UNITED STATES PATENTS 1,026,436 5/1912 Gregg. 1,577,036 3/1926 Kniefel 17-30 2,295,317 9/1942 Young 30299 2,801,540 8/1957 Rondeau 73-150 FOREIGN PATENTS 505,732 8/1930 Germany.

OTHELL M. SIMPSON, Primary Examiner.

R. V. PARKER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,389,463 June 25, 1968 Gene Gerek et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specification, lines 3 and 4, "Gene Gerek, 114-A Shad)r Ave., Cheswick, Pa. 15024, and Ralph R. Gcerchi, R.D, 1, Renfrew, Pa. 16053" should read Gene Gerek, Cheswick, Pa. and Ralph R. Cicerchi, Renfrew, Pa., assignors to PPG Industries, Inc., Pittsburgh, Pa. a corporation of Pennsylvania Signed and sealed this 25th day of November 1969.

(SEAL) Attest: Edward M.F1ercher,1r. WILLIAM E. SCHUYLER, IR.

Attestng Officer Commissioner of Patents 

1. A TOOL FOR SCORING SOLID MATERIAL COMPRISING A HANDLE AND A CUTTING HEAD, SAID CUTTING HEAD DEFINING AN ENLARGED MEMBER HAVING A PAIR OF SIDE SURFACES AND AN ARCUATE PERIPHERAL SURFACE DISPOSED THEREBETWEEN, SAID PERIPHERAL SURFACE HAVING A PLURALITY OF V-SHAPED CUTTING ELEMENTS, A NOTCH FORMED IN SAID CUTTING HEAD ACROSS THE CUTTING ELEMENTS THEREOF, THE BOUNDARIES OF SAID NOTCH WITH SAID CUTTING ELEMENTS DEFINING CUTTING EDGES, WHEREBY WHEN THE CUTTING HEAD IS DRAWN ACROSS THE SOLID MATERIAL IN THE DIRECTION OF THE CUTTING ELEMENTS WITH THE CUTTING EDGES IN CONTACT WITH THE SURFACE OF THE SOLID MATERIAL, THE SURFACE IS UNIFORMLY AND REPRODUCIBLY SCORED. 